X-ray excited phosphors are well known for their use in medical radiography. Medical X-ray films are typically sensitive to UV, blue or green light and therefore the X-radiation containing the diagnostic information must be converted to lower energy to optimally expose the film. This conversion is done by an intensifying screen comprising an appropriate phosphor as the principal active ingredient.
Phosphors which are suitable for converting X-ray energy to the appropriate lower energy are well known. The specific desirable properties include: high conversion efficiency, low granularity and a low quantity of afterglow emission. Particularly useful are phosphors for use in x-ray intensifying screens which have an emission in the near UV and blue. The most widely known phosphor for this purpose is CaWO.sub.4 which has become the industry standard. There is an ongoing desire in the art to provide UV or blue emitting medical x-ray intensifying screens which have a higher speed than intensifying screens comprising CaWO.sub.4.